The purpose of this proposal is to address a significant gap in the prevention literature about the development of substance use and related problems for Latino youth. The Latino population is the fastest growing ethnic subgroup in the U.S., yet our scientific understanding about mechanisms of risk and protection in the population has lagged far behind the growth rate. While epidemiological data support that Latino youth are at no greater risk for substance use than the general youth population, some data indicate that they might be at greater risk for problems that co-occur with substance use (e.g., school failure, incarceration, poor health). Foreign-born Latino youngsters seem to be at particular risk for such problems, and there is growing evidence that risk for substance use initiation and abuse for Latino youth grows substantially as they become more acculturated to the U.S. society. Theoretical models suggest that acculturation processes along with other contextual factors (e.g., socioeconomic status, social support processes) exert their effects on youngster adjustment indirectly, by impacting more proximal variables (i.e., parenting practices). Strong theoretical foundations in the literature have led to the development and testing of a host of interventions designed to ameliorate potential deleterious effects of acculturation for Latino youngsters. Yet, the empirical basis underlying the theory and applied intervention work is sparse. In fact, few empirical studies have been conducted that examine how changes in acculturation processes unfold over time to predict outcomes for families at different stages in the process. The current study will help fill this gap by examining the developmental pathways towards substance use and related problems for 225 recently immigrated Latino families. The prospective, longitudinal design will employ multiple methods and agents to assess family process variables cross-sectionally across up to a 14-year time in residency period, and allows for longitudinal examination of individual family trajectories across a three-year adjustment period. The aims are to: (1) examine the longitudinal effects of acculturation processes, social contexts, and social support processes on family environment, parenting practices, and youth substance use and related problems for immigrant Latino families;(2) examine the effects of years in U.S. residency on the relationship between acculturation processes and the development of youngster substance use and related problems for immigrant Latino families;and (3) test an integrative theoretical model based on social interaction learning theory that specifies mediating effects of family environment and parenting practices on the relationships between macrosystem and exosystem factors (i.e., acculturation processes, social contexts, and social support processes) and substance use and related problems for immigrant Latino youth and their families.